As electronic components have become faster and more powerful, thermal management has become a critical issue. Specifically, all electronic components produce heat when operating. To ensure that the electronic components achieve optimal performance and dependability, this heat must be dissipated. Thus, in applications involving the use of these faster and more powerful electronic components, measures have to be taken to remove the excess heat that is produced.
One application in which faster and more powerful electronics have made thermal management a critical design issue is repeater enclosures for digital telecommunications systems. In a digital telecommunications system, repeaters are used to repeat digital signals in order to overcome signal degradation when an end user is located a long distance from the service provider. A repeater enclosure typically houses a plurality of repeater cards that include electronics that produce heat. Moreover, repeater enclosures are frequently located outdoors where they can be subject to extreme solar loads.
Older repeater enclosures frequently did not have any mechanism for controlling heat because the electronics did not generate large amounts of heat. More recently, repeater enclosures have included aluminum heat sinks surrounding the electronics for removing the excess heat. However, because the heat given off by the electronics must travel through the air to the heat sink and then to the outer housing, the heat sinks have a high thermal resistance and thus remove heat very inefficiently. Moreover, the heat sinks make the enclosures very large and heavy. An active cooling system such as fans is generally not an option on equipment such as repeater enclosures because the enclosure is not connected to an electricity source.
The thermal dissipation limitations of existing repeater enclosures are a particular problem with telecommunication systems designed to handle higher-capacity and higher-speed data transmission such as HDSL4 type systems. These systems require the use of more powerful repeater cards, which, in turn, generate more heat. Because conventional repeater enclosures remove heat very inefficiently, only a limited number of these more powerful repeater cards can be stored in a conventional enclosure before the heat in the enclosure reaches an unacceptable level, particularly in locations where heavy solar loading is an issue.